METHODS AND SYSTEMS FOR EVALUATING VOICE OVER WI-FI (VoWiFi) CALL QUALITY

ABSTRACT

A method, a device, and a non-transitory storage medium provide receiving a plurality of voice call quality values and values for a plurality key performance indicators (KPIs) related to voice over Wi-Fi voice call quality; selecting a subset of the plurality of KPIs based on a correlation between each KPI and the voice call quality value; performing a plurality of discrete regression analyses based on the subsets of the plurality of KPIs and the voice call quality values to generate a plurality of regression results; determining an accuracy for each of the plurality of regression results; assigning weights to each of the plurality of regression results based on the determined accuracies; and combining the plurality of regression results using the assigned weights to generate a final combined estimated VoWiFi voice call quality algorithm that accurately predicts the voice call quality value based on values for the selected subset of the plurality of KPIs.

BACKGROUND

One factor that customers take into account when selecting a wirelessoperator is the quality of wireless voice calls. To address call qualityand to also offload voice traffic off of legacy third generation (3G)cellular networks, wireless carriers have introduced the capability ofcarrying voice traffic over high speed fourth generation (4G) networks,also referred to as voice over long term evolution (LTE) or VoLTE.

Unfortunately, in some circumstances, voice traffic over LTE (or other4G networks) may suffer performance limitations in indoor environments,or environments that are located remotely from a suitable base station.To address these potential limitations, wireless service providers havedeveloped the capability of leveraging existing local wireless networks,i.e., wi-fi networks, for voice traffic in instances in which theperceived quality of the wi-fi network is greater than the perceivedquality of the LTE connection. However, determining which network toutilize in a given instance can be difficult to ascertain and should bebased on accurate determinations or estimations of call quality.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord withthe present teachings, by way of example only, not by way of limitation.In the figures, like reference numerals refer to the same or similarelements.

FIG. 1 is a diagram illustrating an exemplary environment forimplementing the voice over Wi-Fi (VoWiFi) call quality assessmentmethodology described herein;

FIG. 2 is a block diagram of an exemplary embodiment of a VoWiFi voicecall quality assessment device of FIG. 1;

FIG. 3 is a diagram illustrating exemplary components of a device thatmay correspond to one or more of the devices illustrated herein;

FIG. 4 is a process flow diagram that conceptually illustrates anexemplary operation of training logic and testing logic of FIG. 2 interms of the data stored in the storage of FIG. 2;

FIG. 5 is a graph depicting exemplary predicted VoWiFi scores relativeto the traditional call quality scores when a VoWiFi voice call qualityalgorithm has been properly tuned;

FIG. 6 is a three dimensional graph illustrating predicted VoWiFi scoresrelative to two selected key performance indicators (KPIs);

FIG. 7 is a flow diagram illustrating an exemplary process fordetermining VoWiFi call quality consistent with embodiments describedherein; and

FIG. 8 is a flow diagram illustrating an exemplary process fordetermining an estimated VoWiFi voice call quality score.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant teachings. However, it should be apparent that the presentteachings may be practiced without such details. In other instances,well known methods, procedures, components, and/or circuitry have beendescribed at a relatively high-level, without detail, in order to avoidunnecessarily obscuring aspects of the present teachings.

Systems and methods are described herein for evaluating voice over wi-fi(VoWiFi) call quality in relation to conventionally or traditionallydetermined voice call quality measurements performed using a PerceptualObjective Listening Quality Assessment (POLQA) score.

According to some aspects of the subject technology, a computing devicereceives multiple training data points. Each data point in the multipletraining data points includes a traditionally derived VoWiFi voice callquality value and values for at least a subset of a set of keyperformance indicators (KPIs) related to VoWiFi voice call quality. TheVoWiFi voice call quality value may be a POLQA score or another measureof VoWiFi voice call quality. The multiple data points may includemeasured data points from a Long Term Evolution (LTE) cellular networkor any other cellular network as well as data points relating to thewireless (e.g., Wi-Fi) network or networks to which a mobile device isconnected, which may be referred to as radio frequency (RF) data points.The network indicator data may represent one or more values of one ormore network performance attributes of the network(s) to which a mobiledevice is connected. The RF data may indicate an RF quality (e.g., oneor more values of one or more RF quality factors) of the network(s) towhich a mobile device is connected.

In some cases, the traditional or legacy voice call quality value (e.g.,the POLQA score) may be calculated by comparing a local recording of aspeaker speaking into a local microphone and a remote recording of thespeaker speaking over a VoWiFi connection. The local microphone may beproximate (e.g., within 1 meter or within 5 meters) to a speaker, whilethe remote recording may be made using a VoWiFi phone call to adestination at which the speaker cannot be heard without the aid oftelephone technology. The remote recording may be made, for example, 1kilometer, 100 kilometers, or 1000 kilometers away from the speaker. Therecordings may be played to various test subjects, and the test subjectmay provide an opinion score as to how “good” and “understandable” theremote recording is, relative to the local recording. For example, thetest subject may be asked to rank the goodness or understandability ofthe remote speaker on a scale of 0 through 10, with 0 representing “Icannot understand the remote speaker at all,” and 10 representing “I canunderstand the speaker as though he/she were standing right next to me.”A Mean Opinion Score (MOS) of the opinion scores by the tests subjectsmay be calculated, for example, based on a mean of the 0 through 10rankings described above.

Unfortunately, the above-described method of determining the voicequality value (e.g., the POLQA score) and other techniques that directlyevaluate audio features are extremely cumbersome and costly toimplement. For example, each evaluation requires professional hardware,such as high definition recorders, headphones, and playback devices, aswell as significant human effort. Hence, direct evaluation of audiofeatures is difficult to perform on a large-scale basis. Moreover, thedirect evaluation of audio features does not analyze the root cause ofpoor voice quality, and is thus unable to provide a mobile carrier withsufficient information gain (entropy) that allows the mobile carrier tooptimize one or more aspects of the mobile network in order to remedythe poor voice quality.

To remedy these issues and as described herein, an approximation orestimation of the VoWiFi voice call quality score for VoWiFi calls maybe determined by statistically, and autonomously, evaluating objectivedata relating to the calls. More specifically, the methods and systemsdescribed herein may facilitate voice quality assessment based onnetwork indicator data and RF data measured by a network device, such asa mobile device or a combination of a mobile device and other networkcomponents, such as a base station, an access point, etc. By not basingthe voice quality assessment on audio features (i.e., recorded audioclips), the methods and systems may minimize the hardware and humaneffort needed to determine voice call quality scores on a large-scalebasis within a mobile network.

Moreover, the methods and systems provide a quantified causalrelationship between voice quality and deviation in network conditions,and may thereby allow a mobile carrier to more readily assess and remedyissues within the mobile network that have been demonstrably shown toresult in poor voice quality. The voice quality model used in accordancewith the methods and systems described herein may be calibrated tooutput voice call quality scores that are within a predeterminedpercentage of voice call quality scores generated by a POLQA system,such as that described above. Hence, the voice call quality scoresgenerated by the methods and systems described herein may be comparableto those generated by POLQA, which is the recognized standard forquantified voice call quality scores.

In one embodiment, network indicator and/or RF features included in aset of training data training may be initially evaluated to ascertainparticular key performance indicators (KPIs) and/or combinations of KPIsthat are most highly correlated to the traditional voice call qualityscore. Using the identified KPIs as independent (predictor) variablesand the traditional voice call quality score as the dependent (outcome)variables, a plurality of distinct regression analyses are performed.Each regression result may be weighted based on the relative accuracy ofeach regression analysis. The distinct regression results are thencombined and re-weighted to generate a final VoWiFi voice call qualityalgorithm that most closely approximates or predicts the traditionalvoice call quality score for a given set of selected KPIs.

Once the VoWiFi voice call quality algorithm has been determined, theselected KPIs from testing data, such as live data, or data for which atraditional POLQA score has not been determined, may be evaluated basedon the final VoWiFi voice call quality algorithm to generate anestimated or predicted voice call quality score.

FIG. 1 is a diagram illustrating an exemplary environment 100 forimplementing the VoWiFi call quality assessment methodology describedherein. As shown, environment 100 includes, for example, a cellularaccess network 102 that includes a VoWiFi voice call quality assessmentdevice 104, a Wi-Fi access network 106, an Internet Protocol (IP)network 108, and a plurality of mobile devices 110-1 to 110-n(individually referred to as mobile device 110, or collectively asmobile devices 110).

Environment 100 may be implemented to include wired, optical, and/orwireless connections among the devices and the networks illustrated,where appropriate. A connection may be direct or indirect and mayinvolve one or more intermediary or additional devices not illustratedin FIG. 1.

Cellular access network 102 comprises components that facilitateInternet Protocol-based voice calls (e.g., non-circuit switched calls)between mobile devices 110. For example, cellular access network 102 maybe a long term evolution (LTE) 4G wireless network and may include oneor more devices that are physical and/or logical entities interconnectedvia standardized interfaces. Cellular access network 102 provideswireless packet-switched services and wireless IP connectivity to userdevices (such as mobile devices 110) to provide, for example, data,voice, and/or multimedia services. Although not depicted in FIG. 1, itshould be understood that cellular access network 102 includes variouscomponents associated with providing cellular voice and data services,such as a plurality of base station devices (e.g., evolved node B(eNodeB) devices), as well as an evolved packet core (ePC) that includesa mobility management entity, serving and packet data network gatewaydevices, a home subscriber server, etc.

VoWiFi voice call quality assessment device 104 may be implemented as aserver or other computational device that receives data corresponding toa plurality of training VoWiFi calls. In some embodiments, VoWiFi voicecall quality assessment device 104 may be integrated with the ePC of thecellular access network 102, while in other embodiments, VoWiFi voicecall quality assessment device 104 may be located within IP network 108.

Consistent with embodiments described herein, the training data mayinclude KPIs relating to network and radio frequency (RF) measurements,as well as traditionally ascertained voice call quality scorescorresponding to each call.

As described in additional detail below, VoWiFi voice call qualityassessment device 104 generates a voice quality model based on thereceived training data. The voice quality model may be optimized togenerate scores that approximate the traditional voice call qualityscores, but without the costs associated with such a traditional scoringmechanism. In one embodiment, a KPI selection methodology is utilized toidentify the particular KPIs in the training data that most closelycorrelate to the traditional voice call quality score (eitherindividually, or in combination with one or more other KPIs). Once theset of correlated KPIs has been determined, a plurality of discretestatistical analyses may be performed using data that corresponds to theset of correlated KPIs and the traditional voice call quality scoresthat correspond to those KPIs in attempt to model or predict voice callquality score for any given set of correlated KPIs.

As described in detail below, in some embodiments, the plurality ofdiscrete statistical analyses include a number of different multipleregression calculations that each result in independent regressionresults based on the selected training data (e.g., the given sets ofKPIs and their corresponding traditional voice call quality scores).Because each regression calculation may result in a more or lessaccurate approximation of the data, each result may be weighted based ontheir individual relative accuracies, often referred to as the R² valuefor the regression. Once each regression has been performed andweighted, the weighted regression results may be combined and an optimalweight for the set of regressions may be determined.

Once the optimal weight for the aggregate set of regressions isdetermined, an estimated voice call quality score may be confidentlycalculated for test or live data. The estimated voice call quality scoremay approximate the value of a traditional voice call quality score thatcorresponds to the data, without the necessity for acoustic modelcomparisons or human intervention.

Consistent with embodiments described herein, the individual andaggregated regression calculations may be periodically updated orrefined based on additional data sets to reflect potential changes innetwork conditions that may cause a modification in the correlation ofnetwork conditions to a suitable voice call quality score.

Wi-Fi access network 106 comprises a wireless local area network (WLAN)that operates to provide wireless access to a data connection from anInternet service provider (ISP). Although not shown in FIG. 1, Wi-Fiaccess network 108 may include a home gateway, access point, or routerdevice that supports the wireless connection to mobile devices 110, aswell as corresponding ISP devices (e.g., optical or coaxial terminals,head end components, etc.) configured to provide Internet access toconnected mobile devices 110.

IP network 108 may include one or multiple networks of one or multipletypes. For example, IP network 108 may include the Internet, the WorldWide Web, an IP Multimedia Subsystem (IMS) network, a cloud network, awide area network (WAN), a metropolitan area network (MAN), a serviceprovider network, a private IP network, some other type of backendnetwork, and so forth. IP network 108 may include, for example, an IMSnetwork, which may provide data and multimedia services to mobiledevices 110.

Mobile device 110 includes a device that has computational and wirelesscommunicative capabilities. Mobile device 110 may be implemented as acellular telephone, such as a smart phone, or alternatively, may beimplemented as a non-cellular device, such as a laptop or tabletcomputing device. Mobile device 110 may or may not be operated by auser. According to an exemplary embodiment, mobile device 110 includes aVoWiFi quality client tool 112 for providing a device interface toVoWiFi voice call quality assessment device 104.

FIG. 2 is a block diagram of an exemplary embodiment of VoWiFi voicecall quality assessment device 104. As briefly described above, VoWiFivoice call quality assessment device 104 is configured to assess voicequality of mobile telephones operating on one or more wireless networks,such as an LTE or Wi-Fi network. As shown, VoWiFi voice call qualityassessment device 104 may include, without limitation, training logic202, testing logic 204, and storage 206 selectively and communicativelycoupled to one another. Although components 202-206 are shown to beseparate elements in FIG. 1, any of these components may be combinedinto fewer elements, such as into a single component, or divided intomore components as may serve a particular implementation.

Additionally or alternatively, one or more of the components 202-206 maybe omitted from VoWiFi voice call quality assessment device 104 and maybe positioned external to or remote from VoWiFi voice call qualityassessment device 104. For example, storage 206 may be located remotelyrelative to VoWiFi voice call quality assessment device 104 and may becommunicatively coupled to VoWiFi voice call quality assessment device104 via one or more network connections. Components 202-206 of VoWiFivoice call quality assessment device 104 may include or be otherwiseimplemented by one or more computing devices specifically configured toperform one or more of the operations described herein. In suchimplementations, VoWiFi voice call quality assessment device 104 may bereferred to as a computing device-implemented system.

Storage 206 may store detection data generated and/or used by traininglogic 202 and/or testing logic 204. For example, storage 206 maycomprise one or more database structures for storing voice quality modeldata 208 representative of a voice quality model built by training logic202. Storage 206 may also store training data 210 used by training logic202 to build the voice call quality model, and testing data 212 used bytesting logic 204 to generate a voice call quality score for mobiledevices 110. For example, as described above, training data 210 mayinclude KPI data and traditional voice call quality values (e.g., POLQAscores) for a plurality of sample or training calls and testing data 212may include KPI data for calls for which a predicted or estimated voicecall quality score is to be determined. Storage 206 may store additionalor alternative data as may serve a particular implementation. Datastored by storage 206 may be accessed by system 100 from any suitablesource, including a source internal or external to VoWiFi voice callquality assessment device 104.

Training logic 202 may build the voice quality assessment model (alsoreferred to as the voice quality assessment algorithm) that may besubsequently used to generate voice call quality scores that quantify aquality of voice communications for mobile devices at various locationswithin a cellular or wi-fi network. In particular, as briefly describedabove, training logic 202 may facilitate selection of most highlycorrelated KPIs and may perform a number of different multipleregression analyses and weight determinations to accurately model avoice call quality score outcome based on a given set of predictor KPIs.

Testing logic 204 may use the voice quality assessment model built bytraining logic 202 to derive a voice call quality score for a mobiledevice 110 coupled to cellular access network 104 and Wi-Fi accessnetwork 106. To this end, testing logic 204 may receive, from a mobiledevice 110 operating on cellular access network 104 and Wi-Fi accessnetwork 106, a test record that includes network indicator data and RFdata both measured by the mobile device 110 while the mobile device 110is at a location within the cellular and Wi-Fi networks 104/106. Testinglogic 204 may then utilize the voice call quality model generated bytraining logic 202 to accurately predict a voice call quality scoreassociated with the received call KPI data. In some embodiments, thepredicted voice call quality score may be used by mobile devices 110 todetermine when to handoff calls from cellular access network 104 toWi-Fi access network 106 or vice-versa.

FIG. 3 is a diagram illustrating exemplary components of a device 300.Device 300 may correspond, for example, to a component mobile device110, VoWiFi voice call quality assessment device 104, mobile devices, ora component within cellular access network or Wi-Fi access network.Alternatively or additionally, such devices may include one or moredevices 300 and/or one or more components of device 300.

Device 300 may include a bus 310, a processor 320, a memory 330, aninput component 340, an output component 350, and a communicationinterface 360. Although FIG. 3 shows exemplary components of device 300,in other implementations, device 300 may contain fewer components,additional components, different components, or differently arrangedcomponents than those depicted in FIG. 3. For example, device 300 mayinclude one or more switch fabrics instead of, or in addition to, bus310. Additionally, or alternatively, one or more components of device300 may perform one or more tasks described as being performed by one ormore other components of device 300.

Bus 310 may include a path that permits communication among thecomponents of device 300. Processor 320 may include a processor, amicroprocessor, or processing logic that may interpret and executeinstructions. Memory 330 may include any type of dynamic storage devicethat may store information and instructions, for execution by processor320, and/or any type of non-volatile storage device that may storeinformation for use by processor 320. Input component 340 may include amechanism that permits a user to input information to device 300, suchas a keyboard, a keypad, a button, a switch, etc. Output component 350may include a mechanism that outputs information to the user, such as adisplay, a speaker, one or more light emitting diodes (LEDs), etc.

Communication interface 360 may include a transceiver that enablesdevice 300 to communicate with other devices and/or systems via wirelesscommunications, wired communications, or a combination of wireless andwired communications. For example, communication interface 360 mayinclude mechanisms for communicating with another device or system via anetwork. Communication interface 360 may include an antenna assembly fortransmission and/or reception of RF signals. For example, communicationinterface 360 may include one or more antennas to transmit and/orreceive RF signals over the air. In one implementation, for example,communication interface 360 may communicate with a network and/ordevices connected to a network. Alternatively or additionally,communication interface 360 may be a logical component that includesinput and output ports, input and output systems, and/or other input andoutput components that facilitate the transmission of data to otherdevices.

Device 300 may perform certain operations in response to processor 320executing software instructions contained in a computer-readable medium,such as memory 330. A computer-readable medium may be defined as anon-transitory memory device. A memory device may include space within asingle physical memory device or spread across multiple physical memorydevices. The software instructions may be read into memory 330 fromanother computer-readable medium or from another device. The softwareinstructions contained in memory 330 may cause processor 320 to performprocesses described herein. Alternatively, hardwired circuitry may beused in place of or in combination with software instructions toimplement processes described herein. Thus, implementations describedherein are not limited to any specific combination of hardware circuitryand software.

Device 300 may include fewer components, additional components,different components, and/or differently arranged components than thoseillustrated in FIG. 3. As an example, in some implementations, a displaymay not be included in device 300. In these situations, device 300 maybe a “headless” device that does not include input component 340.Additionally, or alternatively, one or more operations described asbeing performed by a particular component of device 300 may be performedby one or more other components, in addition to or instead of theparticular component of device 300.

FIG. 4 is a process flow diagram that conceptually illustrates anexemplary operation of training logic 202 and testing logic 204 in termsof the data stored in storage 206. As shown, the VoWiFi voice callquality algorithm generated by training logic 202 is derived (402) basedon a pool of available KPI values 404 and a set of traditionallycalculated call quality scores 406 retrieved from training data 210.

To derive the VoWiFi voice call quality algorithm, training logic 204may initially perform feature selection on the pool of KPI values 404 todetermine the most correlative KPI values to the traditionallycalculated call quality scores 406. In one implementation, thecorrelation of each possible KPI (e.g., each KPI included in the KPIpool 404) to the corresponding training data voice call quality score(e.g., the POLQA score) may be determined using a linear correlationtechnique, such as a Pearson correlation or a ranked Pearsoncorrelation, which is known as a Spearman correlation. The correlationanalysis ascertains the extent to which a modification of one variableaffects another, with a perfect positive correlation (e.g., an increasein variable A directly correlates to an increase in variable B) beingindicated by a value of 1, a perfect negative correlation (e.g., anincrease in variable A directly correlates to a decrease in variable B)being indicated by a value of −1 and a lack of correlation beingindicated by a value of 0. A Spearman correlation is sometimesadvantageous relative to a general Pearson correlation in that it isless sensitive to statistical outliers by virtue of the rankings of thedata being used to perform the correlation analysis.

In other embodiments, a decision tree learning methodology is used todetermine the most correlative KPIs by leveraging gini impurity orinformation gain to determine the most significant KPIs.

In an exemplary embodiment, such a KPI selection process may determinethat the most correlative KPIs for evaluating VoWiFi call qualityinclude real time protocol (RTP) packet loss percentage, RTP jitter, RTPlatency, RTP gap ratio, RTP session duration, packet data convergenceprotocol (PDCP) throughput, radio link control (RLC) throughput, thenumber of physical downlink shared channel physical resource blocks(PDSCH.PRB), a PDSCH block error rate (BER), and a handover happeningindicator value.

Once the most correlative KPIs have been determined, the discretemultiple regression analyses are performed using some or all of the setof selected KPIs to derive the VoWiFi voice call quality algorithm. Asbriefly described above, the components of the VoWiFi voice call qualityalgorithm are tuned or weighted so as to bring the mean error rate ofany calculated or predicted call quality score 408 to within about 0-10%of the traditional call quality score and preferable within about 5%. Asdepicted in FIG. 4, the derivation and tuning of the VoWiFi voice callquality algorithm are fundamentally recursive in that the generatedalgorithm may be continually or periodically adjusted to reflect eitheradditional data, or to reflect changes in the permissible mean errorrate.

FIG. 5 is a graph depicting an exemplary predicted VoWiFi scoresrelative to the traditional call quality scores when the VoWiFi voicecall quality algorithm has been properly tuned. In this example, themean error rate of the predicted VoWiFi scores is approximately 5%, witha corresponding mean accuracy rate of approximately 95%.

FIG. 6 is a three dimensional graph illustrating predicted VoWiFi scoresrelative to two of the selected KPIs. In this example, the two selectedKPIs include packet loss percentage and jitter, both of which are highlycorrelative to predicted VoWiFi voice call quality score.

FIG. 7 is a flow diagram illustrating an exemplary process 700 fordetermining VoWiFi call quality consistent with embodiments describedherein. In one implementation, process 700 may be implemented by adedicated VoWiFi voice call quality assessment device 104. In anotherimplementation, process 700 may be implemented by a component ofcellular access network 102 that incorporates the features of VoWiFivoice call quality assessment device 104 or in conjunction with one ormore other devices in network environment 100.

Referring to FIG. 7, process 700 may include receiving and storingtraining data, such as network and RF KPI data, for a plurality ofsample VoWiFi calls (block 702). For example, training logic 202 mayreceive VoWiFi call data, e.g., from a client application executing onmobile devices 110. At block 704, traditional or conventional voice callquality scores may be determined based on the call data. For example, asdescribed above, the traditional voice call quality scores (e.g., thePOLQA scores) may be determined by comparing a local recording of aspeaker speaking into a local microphone and a remote recording of thespeaker speaking over the VoWiFi connection. The recordings may beplayed to various test subjects, and results in a Mean Opinion Score(MOS) representative of the call quality.

In some embodiments, the traditional voice call quality scores may bedetermined outside of the VoWiFi voice call quality assessment device104, with VoWiFi voice call quality assessment device 104 merelyreceiving the resultant scores that correspond to the received KPI data.In other embodiments, VoWiFi voice call quality assessment device 104may act as a repository for receiving the call data and recordings forreview by the test subjects. In any event, at block 706, the traditionalvoice call quality score is stored for subsequent use by VoWiFi voicecall quality assessment device 104.

Next, using the stored KPI data and the corresponding traditional voicecall quality scores, KPI selection is performed (block 708). Forexample, as briefly described above, training logic 202 may calculatecorrelation indices (e.g., correlation coefficients) for each KPI inrelation to the traditional voice call quality scores. For example, aSpearman correlation may be performed to identify the most correlativeKPIs. More specifically, a pair-wise relationship of voice call qualityscores and KPIs may be visualized. The KPIs showing high impact on thevoice call quality score may be selected as independent variablecandidates.

In an exemplary embodiment, the most correlative KPIs may be selectedfor inclusion into the predicted voice call quality score algorithmgeneration process. In particular, a number of KPIs ranging from 3 to 12may be included with varying levels of resulting complexity. As setforth above, exemplary KPIs selected for inclusion may include RTPPacket loss percentage, RTP Jitter, RTP Latency, RTP Gap Ratio, RTPSession Duration, PDCP Throughput, RLC Throughput, PDSCH.PRB, PDSCH BER,and the handover happening indicator value.

At blocks 710-1 to 710-n, the selected KPIs and the traditional voicecall quality scores are subjected to a plurality, n, of differentregression analyses, where n could range from 3 to 8. For example,training logic 202 may perform a linear regression (710-1), a secondorder polynomial regression (710-2), a third order polynomial regression(710-3), a lasso regression (710-4), a ridge regression (710-5), anelastic regression (710-6), and a generalized additive model regression(710-7).

Furthermore, in some embodiments, at block 710-n, in addition to thecalculation of these seven known statistical regression models, anAdaptive Local Weight Scatterplot Smoothing (A-LOESS) regression mayalso be performed. It is to be understood that additional, fewer ordifferent regressions can be used. A-LOESS improves traditional LOESS byadaptively computing a proper or optimized window size during theregression, instead of the fixed window size in traditional LOESS. Morespecifically, the voice call quality scores are placed into differentbins, and the window sizes for each local set are dynamically adjustedbased on the distribution density of each bin. For example, in oneimplementation, 9 bins may be established according to the scale of thetraditional voice call quality score, from bin0 that includes scoresfrom 0 to 0.5 to bin8 that includes scores from 4.5 to 5, etc.

An initial window width may be set to 1=100 of range of sample points,and a scatterplot of all measured voice call quality scores may beplotted in an ascending order. Let f(x) denote the scatterplot function,where x is from 1 to the number of sample points. First, for each bin a(e.g., bin(0 to bin8) we compute its distribution density by integratingthe value of the scatterplot function in its range as follows:

y _(a)=∫_(ƒ) ₋₁ _((0.5a)) ^(ƒ) ⁻¹ ^((0.5a+0.5)) ƒ(x)dx, (i=0, . . . , 8)

Subsequently, the value of y_(a) is sorted in ascending order. LetS(y_(a))min represent the bin with minimum y_(a), S(y_(a))med representthe bin that has the median value of y_(a), and S(y_(a))max representthe bin with maximum y_(a). Next, the window sizes are dynamicallycalculated by sorting the results, as follows:

${win\_ size} = \left\{ \begin{matrix}{{\frac{0.5 + {0.125 \cdot S}}{100} \cdot N},} & {{{{if}\mspace{14mu} S} = 0},\ldots \mspace{14mu},4} \\{{\frac{1 + {0.25 \cdot \left( {S - 4} \right)}}{100} \cdot N},} & {{{{if}\mspace{14mu} S} = 5},\ldots \mspace{14mu},8,}\end{matrix} \right.$

Finally, the adaptive window size may be calculated to perform LOESSregression to the voice call quality score based on the selected KPIs.

Still referring to FIG. 7, once each individual regression has beenperformed, the accuracy of each regression is determined (blocks 712-1to 712-n). For example, training logic 202 may calculate a mean errorrate for each regression to determine the variance of the predictedvoice call quality scores relative to the actual voice call qualityscore determined by the conventional means. In an alternativeimplementation, the accuracy of each regression may be determined usinga least squares fit analysis. Using the accuracy determinations for eachregression, weights are applied to each regression result, with theaggregate weights totaling to 1, such that combination of all of theresulting scores when their respective weights are applied willapproximate the voice call quality score block 714-1 to 714-n).

Once individual weights have been determined for each regression result,the results are combined to generate a combined estimated VoWiFi voicecall quality algorithm (block 716). Next, an accuracy calculation isperformed on the combined estimated VoWiFi voice call quality algorithmto calculate a weight (block 718) for applying to the combined score toallow it to best approximate the traditionally ascertained voice callquality score. For example, the weight may be selected to result inestimated VoWiFi voice call quality scores having a mean error rate thatis within approximately 0-10% of the traditionally generated voice callquality scores (e.g., the POLQA scores). Using the determined weight, afinal combined estimated VoWiFi voice call quality algorithm may begenerated (block 720).

In one embodiment, Quadratic Programming is used to determine theoptimum weight. For example, assume that for a given voice call qualityassessment we have 7 regression fitted series: Y1, Y2, . . . Y7, andassume that Y is the traditionally measured voice call quality score.Quadratic Programming may be performed to solve for the weight thatminimize the square sum of the errors.

FIG. 8 is a flow diagram illustrating an exemplary process 800 fordetermining an estimated VoWiFi voice call quality score using thecombined estimated VoWiFi voice call quality algorithm derived in themanner described in relation to FIG. 7. In one implementation, process800 may be implemented by voice call quality assessment device 104, suchas testing logic 204. In another implementation, process 800 may beimplemented by a component of cellular access network 102 or,alternatively, a component or application executing on mobile device110.

As shown in FIG. 8, process 800 begins when a new measurement isreceived (block 802). For example, testing logic 204 may receive a setof KPIs relating to a VoWiFi call from mobile device 110. In block 804,selected ones in the received set of KPIs are inserted into the combinedestimated VoWiFi voice call quality algorithm to generate an estimatedVoWiFi voice call quality score. The estimated VoWiFi voice call qualityscore may be stored (block 806). For example, testing logic 204 maystore the estimated VoWiFi voice call quality score in storage 206 fordiagnostic or evaluative purposes. In some embodiments, an indication ofthe estimated VoWiFi voice call quality score is output to, for example,the mobile device 110 from which the set of KPIs on which the score isbased is received. In other embodiments, an indication of the estimatedVoWiFi voice call quality score may be used as a basis for determiningwhether to handoff a voice call to carrier access network 102, e.g., asa voice over LTE (VoLTE) call.

In some embodiments, testing logic 204 may provide, using outputcomponent 350 of testing logic 204 or another output device, such asmobile device 110, an indication of one or more of the input KPIs thatmost impacted the estimated VoWiFi voice call quality score. In thismanner, VoWiFi voice call quality assessment device 104 may inform usersregarding what KPI(s) to change or address to improve the predictedVoWiFi voice call quality score in a case where the predicted VoWiFivoice call quality score is insufficient. VoWiFi voice call qualityassessment device 104 may be provided with price(s) for changing theKPI(s), and may indicate, based on the price(s), which KPI(s) should bechanged to cause a greatest increase in VoWiFi voice call quality perunit of currency (e.g., dollar) spent.

The foregoing description of embodiments provides illustration, but isnot intended to be exhaustive or to limit the embodiments to the preciseform disclosed. Accordingly, modifications to the embodiments describedherein may be possible.

Unless otherwise stated, all measurements, values, ratings, positions,magnitudes, sizes, and other specifications that are set forth in thisspecification, including in the claims that follow, are approximate, notexact. They are intended to have a reasonable range that is consistentwith the functions to which they relate and with what is customary inthe art to which they pertain.

Except as stated immediately above, nothing that has been stated orillustrated is intended or should be interpreted to cause a dedicationof any component, step, feature, object, benefit, advantage, orequivalent to the public, regardless of whether it is or is not recitedin the claims.

It will be understood that the terms and expressions used herein havethe ordinary meaning as is accorded to such terms and expressions withrespect to their corresponding respective areas of inquiry and studyexcept where specific meanings have otherwise been set forth herein. Theterms “comprises,” “comprising,” or any other variation thereof, areintended to cover a non-exclusive inclusion, such that a process,method, article, or apparatus that comprises a list of elements does notinclude only those elements but may include other elements not expresslylisted or inherent to such process, method, article, or apparatus. Anelement proceeded by “a,” “an,” and “the” does not, without furtherconstraints, preclude the existence of additional identical elements inthe process, method, article, or apparatus that comprises the elementand are intended to be interpreted to include one or more items.Further, the phrase “based on” is intended to be interpreted as “based,at least in part, on,” unless explicitly stated otherwise. The term“and/or” is intended to be interpreted to include any and allcombinations of one or more of the associated items.

In addition, while series of blocks or process steps have been describedwith regard to the processes illustrated in FIGS. 4, 7, and 8, the orderof the blocks may be modified according to other embodiments. Further,non-dependent blocks may be performed in parallel. Additionally, otherprocesses described in this description may be modified and/ornon-dependent operations may be performed in parallel.

The embodiments described herein may be implemented in many differentforms of software executed by hardware. For example, a process or afunction may be implemented as “logic” or as a “component.” The logic orthe component may include, for example, hardware (e.g., processor 320,etc.), or a combination of hardware and software. The embodiments havebeen described without reference to the specific software code since thesoftware code can be designed to implement the embodiments based on thedescription herein and commercially available software designenvironments/languages.

In the preceding specification, various embodiments have been describedwith reference to the accompanying drawings. However, variousmodifications and changes may be made thereto, and additionalembodiments may be implemented, without departing from the broader scopeof the invention as set forth in the claims that follow. Thespecification and drawings are accordingly to be regarded asillustrative rather than restrictive.

As set forth in this description and illustrated by the drawings,reference is made to “an exemplary embodiment,” “an embodiment,”“embodiments,” etc., which may include a particular feature, structureor characteristic in connection with an embodiment(s). However, the useof the phrase or term “an embodiment,” “embodiments,” etc., in variousplaces in the specification does not necessarily refer to allembodiments described, nor does it necessarily refer to the sameembodiment, nor are separate or alternative embodiments necessarilymutually exclusive of other embodiment(s). The same applies to the term“implementation,” “implementations,” etc.

The word “exemplary” is used herein to mean “serving as an example.” Anyembodiment or implementation described as “exemplary” is not necessarilyto be construed as preferred or advantageous over other embodiments orimplementations.

Use of ordinal terms such as “first,” “second,” “third,” etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another, thetemporal order in which acts of a method are performed, the temporalorder in which instructions executed by a device are performed, etc.,but are used merely as labels to distinguish one claim element having acertain name from another element having a same name (but for use of theordinal term) to distinguish the claim elements.

Additionally, embodiments described herein may be implemented as anon-transitory storage medium that stores data and/or information, suchas instructions, program code, data structures, program modules, anapplication, etc. The program code, instructions, application, etc., isreadable and executable by a processor (e.g., processor 320) of acomputational device. A non-transitory storage medium includes one ormore of the storage mediums described in relation to memory/storage 330.

No element, act, or instruction described in the present applicationshould be construed as critical or essential to the embodimentsdescribed herein unless explicitly described as such.

What is claimed is:
 1. A computing-device implemented method comprising:receiving a plurality of training data points, wherein each data pointin the plurality of training data points includes a voice call qualityvalue and values for a plurality of key performance indicators (KPIs)related to voice over wi-fi voice call quality; determining, for eachKPI of the plurality of KPIs and using the plurality of training datapoints, a correlation between the KPI and the voice call quality value;selecting a subset of the plurality of KPIs based on the correlation;performing a plurality of discrete regression analyses based on thesubsets of the plurality of KPIs and the voice call quality values togenerate a plurality of regression results; determining an accuracy foreach of the plurality of regression results; assigning weights to eachof the plurality of regression results based on the determinedaccuracies; combining the plurality of regression results using theassigned weights to generate a final combined estimated voice over Wi-Fi(VoWiFi) voice call quality algorithm that accurately predicts the voicecall quality value based on values for the selected subset of theplurality of KPIs; receiving a new subset of the plurality of KPIs; anddetermining the estimated VoWiFi voice call quality value based on thecombined estimated VoWiFi voice call quality algorithm and the newsubset of the plurality of KPIs.
 2. The computing-device implementedmethod of claim 1, wherein the voice call quality value comprises atraditionally determined Perceptual Objective Listening QualityAssessment (POLQA) score.
 3. The computing-device implemented method ofclaim 1, wherein the selected subset of the plurality of KPIs comprisesat least two KPIs.
 4. The computing-device implemented method of claim3, wherein the selected subset of the plurality of KPIs are selectedfrom real time protocol (RTP) Packet loss percentage, RTP Jitter, RTPLatency, RTP Gap Ratio, RTP Session Duration, packet data convergenceprotocol (PDCP) throughput, radio link control (RLC) Throughput, thenumber of physical downlink shared channel physical resource blocks(PDSCH.PRB), a PDSCH block error rate (BER), and a handover happeningindicator value based on the correlation of each KPI to the voice callquality value.
 5. The computing-device implemented method of claim 1,further comprising: receiving the new subset of the plurality of KPIsfrom a mobile device; and outputting, to the mobile device, anindication of the estimated VoWiFi voice call quality value.
 6. Thecomputing-device implemented method of claim 1, further comprising:determining the correlation using a Spearman correlation technique. 7.The computing-device implemented method of claim 1, wherein performingthe plurality of discrete regression analyses comprises performing anumber of discrete regression analyses, wherein the number ranges from 3to
 8. 8. The computing-device implemented method of claim 7, wherein thenumber of discrete regression analyses comprise a linear regression, asecond order polynomial regression, a third order polynomial regression,a lasso regression, a ridge regression, an elastic regression, ageneralized additive model regression, and an adaptive local weightscatterplot smoothing (A-LOESS) regression.
 9. The computing-deviceimplemented method of claim 7, further comprising: assigning differentweights to the plurality of regression results based on the determinedaccuracy, wherein the total of all weights combines to a value of one.10. The computing-device implemented method of claim 9, furthercomprising: assigning an updated weight to the combined estimated VoWiFivoice call quality algorithm to generate the final estimated VoWiFivoice call quality algorithm.
 11. The computing-device implementedmethod of claim 10, wherein the updated weight is calculated using aquadratic programming technique based on the different weights assignedto plurality of regression results.
 12. A device comprising: acommunication interface; a memory, wherein the memory storesinstructions; and a processor, wherein the processor executes theinstructions to: receive a plurality of training data points, whereineach data point in the plurality of training data points includes avoice call quality value and values for a plurality key performanceindicators (KPIs) related to voice over wi-fi voice call quality;determine, for each KPI of the plurality of KPIs and using the pluralityof training data points, a correlation between the KPI and the voicecall quality value; select a subset of the plurality of KPIs based onthe correlation; perform a plurality of discrete regression analysesbased on the subsets of the plurality of KPIs and the voice call qualityvalues to generate a plurality of regression results; determine anaccuracy for each of the plurality of regression results; assign weightsto each of the plurality of regression results based on the determinedaccuracies; combine the plurality of regression results using theassigned weights to generate a final combined estimated VoWiFi voicecall quality algorithm that accurately predicts the voice call qualityvalue based on values for the selected subset of the plurality of KPIs;receive, via the communication interface, a new subset of the pluralityof KPIs; and determine the estimated voice over Wi-Fi (VoWiFi) voicecall quality value based on the combined estimated VoWiFi voice callquality algorithm and the new subset of the plurality of KPIs.
 13. Thedevice of claim 12, wherein the voice call quality value comprises atraditionally determined Perceptual Objective Listening QualityAssessment (POLQA) score.
 14. The device of claim 12, wherein theselected subset of the plurality of KPIs comprises at least two KPIsselected from real time protocol (RTP) Packet loss percentage, RTPJitter, RTP Latency, RTP Gap Ratio, RTP Session Duration, packet dataconvergence protocol (PDCP) throughput, radio link control (RLC)Throughput, the number of physical downlink shared channel physicalresource blocks (PDSCH.PRB), a PDSCH block error rate (BER), and ahandover happening indicator value based on the correlation of each KPIto the voice call quality value.
 15. The device of claim 12, wherein theprocessor to perform the plurality of discrete regression analysesfurther executes the instructions to perform a number of discreteregression analyses, wherein the number ranges from 3 to
 8. 16. Thedevice of claim 15, wherein the number of discrete regression analysescomprise a linear regression, a second order polynomial regression, athird order polynomial regression, a lasso regression, a ridgeregression, an elastic regression, a generalized additive modelregression, and an adaptive local weight scatterplot smoothing (A-LOESS)regression.
 17. The device of claim 15, wherein the processor furtherexecutes the instructions to: assign different weights to the pluralityof regression results based on the determined accuracy, wherein thetotal of all weights combines to a value of one.
 18. The device of claim17, wherein the processor further executes the instructions to: assignan updated weight to the combined estimated VoWiFi voice call qualityalgorithm to generate the final estimated VoWiFi voice call qualityalgorithm.
 19. A non-transitory, computer-readable storage mediumstoring instructions executable by a processor of a computationaldevice, which when executed cause the computational device to: receive aplurality of training data points, wherein each data point in theplurality of training data points includes a voice call quality valueand values for a plurality key performance indicators (KPIs) related tovoice over wi-fi voice call quality; determine, for each KPI of theplurality of KPIs and using the plurality of training data points, acorrelation between the KPI and the voice call quality value; select asubset of the plurality of KPIs based on the correlation; perform aplurality of discrete regression analyses based on the subsets of theplurality of KPIs and the voice call quality values to generate aplurality of regression results; determine an accuracy for each of theplurality of regression results; assign weights to each of the pluralityof regression results based on the determined accuracies; combine theplurality of discrete regression results using the assigned weights togenerate a final combined estimated voice over Wi-Fi (VoWiFi) voice callquality algorithm that accurately predicts the voice call quality valuebased on values for the selected subset of the plurality of KPIs;receive a new subset of the plurality of KPIs; and determine theestimated VoWiFi voice call quality value based on the combinedestimated VoWiFi voice call quality algorithm and the new subset of theplurality of KPIs.
 20. The non-transitory, computer-readable storagemedium of claim 19, further storing instructions executable by theprocessor of the computational device, which when executed cause thecomputational device to: perform a range of three to eight distinctregression analyses selected from a linear regression, a second orderpolynomial regression, a third order polynomial regression, a lassoregression, a ridge regression, an elastic regression, and a generalizedadditive model regression, and an adaptive local weight scatterplotsmoothing (A-LOESS) regression; assign different weights to results ofthe range of three to eight regression analyses based on the determinedaccuracy, wherein the total of all weights combines to a value of one;and assign an updated weight to the combined estimated VoWiFi voice callquality algorithm to generate the final estimated VoWiFi voice callquality algorithm.